Please look at the training SWAT members receive. Does anyone really think a teacher would have the skill or capacity to shoot before being shot. If you do then I suggest viewing a test of such a proposition. 20/20 trained college age men and women to "defend" themselves with handguns. They received more training than is required for a weapon permit. The result of their training including one person with lots of firearm experience...
'If I Only Had a Gun': Click Here for 20/20 Special | Video - ABC News
How well do cops do in a chaotic situation? In August there was a shooting in NYC near the Empire State Bldg. Police responded and nine people were shot in the confusion. All nine were shot by the NYC police accidentally.